This invention relates to a repeater and, more particularly, to a repeater having particular application in transmitting data, such as remote control data, received at one location to a remote location via AC power lines, and from which remote location the data is recovered and re-transmitted.
In several applications, a common transmission medium is used to communicate several different types of information from one location to another. It is known to segregate individual data channels to facilitate such transmission; and desired data may be recovered by means of receiving circuitry that operates only with a particular channel. Such multiplexing of information typically employs frequency division multiplexing (FDM), time division multiplexing (TDM) and other conventional multiplexing techniques.
When the medium which is used to transmit information also is used to transmit power, as when conventional AC power lines, such as common household wiring, are used as the transmission medium, significant amounts of noise, interference and other disturbances tend to degrade and distort an information signal supplied to that transmission medium. This difficulty is compounded when plural information channels are applied to the transmission medium. For example, difficulties are encountered when AC power lines are used to transmit stereophonic audio signals This problem of interference, distortion and degradation of information signals has been solved in accordance with the techniques discovered by the present inventor and disclosed in copending applications Ser. Nos. 053,355 and 127,793, the disclosures of which are incorporated herein by reference.
Briefly, in the so-called wireless transmission systems disclosed in the aforementioned applications, left-channel and right-channel audio signals modulate separate FM carriers, and these FM signals are transmitted over AC power lines from a source location to a remote location whereat the audio signals are demodulated and used to drive respective output devices, such as left and right loudspeakers. Advantageously, the carrier frequencies of these respective FM carriers are selected such that an harmonic of one does not interfere with the fundamental or harmonic of the other. Of course, a more complete description of wireless transmission systems are found in these pending patent applications.
A typical application of the aforementioned wireless transmission systems is in so-called home entertainment systems. Typically, a source of audio signals, such as a magnetic tape player, a radio receiver, a phonograph record, a compact disk, or the like, is situated in one room of a user's home, and the loudspeakers which are used to reproduce the audio signals provided by that source are located in another room The household wiring provided in the user's home is used as the transmission medium to extend the audio signals from the source to the loudspeakers. A commercial embodiment of this wireless transmission home entertainment system is marketed by Recoton Corporation, the assignee of the present invention, under the designation "Wireless 100 Speaker System".
While the aforementioned wireless transmission system, and particularly the "Wireless 100 Speaker System" has met with commercial success, the fact that the audio signal source and sound reproducing devices are located in separate rooms means that the user must leave the room in which the audio signals are reproduced and enter the room in which the signal source is located if he wishes to make any adjustments in the tone quality or program content to which he is listening. For example, volume adjustments, base/treble adjustments, tape-changing, radio station tuning, disk program selection, or the like must be made directly at the audio signal source. Such adjustments have been simplified by the introduction of remote control units which, typically, are hand-held portable devices that are manually operated by the user to affect any one or more o the aforementioned adjustments. Usually, these devices communicate with the audio signal source by means of infra-red transmission; and infra-red data pulses are transmitted from the remote control unit to a compatible IR detector which recovers and interprets the data transmitted from the remote control unit For example, the data may be encoded as digital pulses, and these pulses are recovered and used to control respective functions. Such pulses may be encoded as different data "words", with each word identifying a particular function together with an incremental increase or decrease in that function In this fashion, volume may be incrementally increased or decreased, the radio broadcast station to which a radio receiver is tuned may be incrementally increased or decreased, base/treble functions may be incrementally increased or decreased, the particular one of several programs prerecorded on a compact disk may be incrementally selected, etc.
Most remote control devices available today operate by means of infra-red transmission, as aforementioned. Other remote control devices which had been commercially available previously utilized ultrasonic signals for transmitting data from the hand-held unit to the compatible detector, and still other devices transmitted data signals by means of low-power radio transmission. However, in all of these devices, and particularly those in which IR transmission is used, the remote control unit must be physically located in the very same room as the compatible detector. Indeed, with IR remote control devices, a line-of-sight is needed for proper operation. It is manifest that, heretofore, the advantages derived from wireless transmission systems, such as the Wireless 100 Speaker System, cannot be fully exploited if the user still must return to the room in which the audio signal source is located. Since many home entertainment systems which are available today utilize IR remote control devices, it is desirable to enable the user of a wireless transmission system to enjoy the use of an IR remote control device (or other wireless remote control devices) with which his home entertainment system may be furnished.
One approach to extending the range of an IR remote control device in a television viewing system is described in U.S. Pat. No. 4,509,211. As described in this patent, a video signal playback device, such as a VCR, is connected to a television receiver by means of conventional wires, such as coaxial cable, twin flat lead, or the like, to supply reproduced video signals from the VCR to the television receiver. An IR detector is connected to the very same wires and is located at the vicinity of the television receiver. Control signals are transmitted to this IR detector from a conventional hand-held remote control unit, and this data is converted to corresponding electrical signals which then are transmitted over these wires to an IR emitter located at the vicinity of the VCR. The data signals supplied via these wires to the IR emitter are converted to IR signals which, in turn, are emitted to the conventional IR detector normally provided at the VCR. Hence, conventional operating functions normally carried out by a VCR located in one room may be controlled from a different room by using a conventional hand-held IR-emitting remote control device.
Unfortunately, the aforementioned extended remote control arrangement relies upon the very same television transmission lines normally provided between a VCR and a television receiver as the transmission medium for the remote control data signals But, the use of separate information transmission lines, such as coaxial cables or twin flat leads, fully defeats the advantages and objectives of the wireless transmission system discussed above. Indeed, the primary purpose of utilizing household wiring as the transmission medium between an audio signal source and loudspeakers (or other audio signal utilization devices) is to avoid the need for stringing additional wires therebetween.